Linear lighting units in which a light emitting diode or other such semiconductor light source is used have been proposed in recent years as lighting units that are an alternative to fluorescent lamps. For instance, in order to increase the luminous flux of light, a lighting unit has been disclosed which comprises a plurality of LED chips mounted along the lengthwise direction of a substrate, and a transparent resin part that is substantially semicylindrical or hog-backed and is formed so as to integrally cover these LED chips entirely. For example, see Japanese published unexamined patent application 2002-299697.
However, because of its narrow illumination range, the above-mentioned lighting unit was not suited to lighting applications in which a wide range is to be uniformly illuminated.